Process Author - Add fields from modules

I am trying to create a workflow, The process has to check a date field from `Product` Module but I didnt see availabe datetime fields from `Product ` Module, As i can get are the Created and Date Modified.

Relationship: Product (one) -to- Task(Many)

Refer the following Image:

I am linking for custom field in Product module like `Delivery Date`.

I have went through sugar doc and other community questions related to similar topic.